Class signaling for telephone systems



Feb. 17, 1931. M.' MA'rHlAs CLASS SIGNA|`ING FOR TELEPHONE`SYSTEMS Fired Deo. s. 1928 4 Sheets-Sheet 1 Feb. 17, 1931. M. MATHlAs 1,792,651

CLASS SIGNALING FOR TELEPHONE SYSTEMS Filed Deo. 3. 1928 4' sheets-sheet 2 NRM Inval-Linz" Feb. 17, 1931. M. MATHlAs 1,792,651

CLASS SIGNALING FOR TELEPHONEl SYSTEMS Feb. 17, 1931. M. MATHlAs 1392,651

CLASS SIGNALING FOR TELEPHONE SYSTEMS Filed Dec. 3, 1928 4 SheetsSheet 4 Inuenin'r Maximilian mi'iiias rn 2P fori-fic e,

MAXIMILIAN ivrA'rrarna er Bnnrirnenmcnnr, assienon To srEtrENs a nnnsxn AKTIENGESELLSCHAFT, or wnnrrnnwnnn, srnmnnssrnn'r, nana BERLIN, GER.-

MANY

Application led Decemcer Si, i928, Serial No.

l The invention relates to telephone systems.

having different classesv of stations, which fdier from one another for examplein the ation of the twodevices notifying to the operator the class to which the calling station belongs. l y

The arrangement'is of particular advantage when the operators positionat` the exfp-f change is notified by an audible signahbecause the clearness of the conversation'is not' 0 Figs. l and 2 of the drawing,

Vreducedbythe functioning of the' devices used for notifying. H K

Examples of the invention are Vshown in the Figsl to 4e. The rectangles enclosing 'theV windings of various relays shown on the drawing indicate that these relays are made slow to release by placing a copper slugon the heel end of the core, or in some other known manner, The invention is notnecessarily limited to these examples. The invention will be further described withY reference to these figures.

when Fig. 2 is placed to the right of Fig. l, show by means of the usual schematic diagram the preferred embodiment of the invention.V The apparatus shown to the'left of the vertical broken line in Fig. 2 is at the coin box station, while that shown to the right ofthis vertical line is the apparatus Vin the exchange. Fig. 2 discloses the apparatus at the operators position.

Fig. 3 shows a modification of the invention in which the oscillator at the operators position is associated with the service trunks extendinglto thisposition.

Fig. 4 shows still another modiiication in which the oscillator associated with the calling station is provided in the exchange and is connected'to the outgoing trunks from the line finders, such as AS1.

rlhe circuits shown in the Figs. 1 and. 2

0 will be described first of all.

CLASS SIGNALNG E SYSTEMS $23,323, and.` in Germany December 29, 1927.

f isstarted up over earth, winding of relay R, contact 2t, microphone, repeater Uel, im-

pulse Contact J ,switch hook HU, contact lt, resistance W2', battery, earth;` and the switch hunts for an ri'dle'group selector. After the preselectors nonnumerical selection, the re lay T is operated over: earth, battery, wind- Ving of the relay- T, wiper @Tof the preselector VW, contact 5m, resistance lYz',eartli, `(parallel thereto overwinding I ofvrelayC, contact A6ft, earth). At the contacts Bt and 4t it switches through ,the ,junction line to the group selector GW, so that the relays A and B are operated in' addition tothe relay C. The

relayVl `is operated over contact 9c (earth,v battery, contact 9c, winding Il of relay C,

contact 8a, rel-ay V1, earth). The insertion of afcoin opens the coininsertion Contact 'MEIQ hence theoperationof the impulse contact J cle-energizes the relay'Aof the,

seized4 group selector at each impulse in known-manner. Inaccordance with the impulses? the' lifting magnet H is energized over: earth, contacts 12'w, 11a, 10111, lifting magnetI-I, battery, earth. When the relay V2, which was energized when the short circuit was removed upon the release'fof the relay A, falls back at the end of the impulse train owing to the Vshort circuit over Contact 805, thev group selector `hunts owing to the rotary magnet Dbeing energized over: earth,

`contacts 18k, 17p, 16122, 151:1, 13d, rotary magnet D, battery, earth. When the group selector has found an idle switchboard position, the relay P is operated over: earth, winding` I and Il of relay P, Contact 20 o1,

wiper c1 of the group selector, 'lead 02,

relayAl, battery, earth; by short "circuiting its winding II over Vthe contact 19p,

relay vP marks engagedA the junction jack to all further calls.` At the switchboard position the 4calling ylamp AL is lighted over: earth, cont-act 24a1,jack contact 7c, calling lamp AL, battery, earth. On inserting the answering plug, the calling lamp AL is disconnected at the j ack Contact K, f

When the operator answers the call, she throws the speaking key in the directionV l and at the same time presses the key Ta, whereby the heating battery of the cathode 5 of the oscillation generator R2 is connected up, thus sending an auxiliary oscillation over the repeater U68 to the junction line. This oscillation, which lies outside the range 0f audibility, in conjunction with the funda- 1oniental frequency generated by the oscillating circuit LC at the coin box station and differing slightly from the auxiliary oscillation (for example 5,000 cycles) and also inaudible, gives rise to an interference oscillation, which is audible. This tone notifies the bperator at 1the exchange position that a f specialistation is calling.

' By releasingthe key Ta, the operator disconnectsitheauxiliary oscillation. The clearf 20 .ness of speech :is not affected, because the oslcillation transmitted from the coinbox statien lies outsidethe range of audibility. The

- audible signal therefore depends ontwo factors,` one ofiwhich is under the control of the special station vand the other being under the @control of the exchange operator. No effec- ,tive signalis given when oneof the two fac- Aitors is suppressed. Hence it is possible to rc- -Inove thefsignal, which affects the clearness of .Y

301 speech, withouthavingto use special switchi ing means, which :react on the signaling de- -vice of; Vthevspecial station.

"Vfhen `thefoperator sets up over her con- `ineetingrz device a connection, for `which a fee 'i35 has mbe-paid, she'requests theysubscriber to insert one or more coins. Thereby difl'erent fcoin contacts (for example MKLMKQ) are .operatediaccording to the kind 0f coin inserted, hence the alterationin frequency at "40 )theoscillationggenerator by meansof difier- Aentfsignals.notifies the operatorof the insegrtioniofthe coins. The above mentioned connecting device is not completelyeshown in lthe-Fig@V because it does not concern `the w winvention.

At the-end ofthe conversation, the connection is released .inknown manner.

shows anarrangement, in which theirieviccs for indicatingto ythe operator Vthe @H diiieigent classes of subscribersi. .stations .leeatecl at the.- seryicc line.

AVhen the` subscriber, by taking down his Areceiver 1)..starts up his preselector to hunt as previously described, the preselector e. ad@

:i1-5551's u ivrestedfwhen a free junction line has been iifound; owinfrwtetherelay T being energized .overtheuiindingiof-relayC 3) and the ,oit normal .contact 3571:. "Thereupon the-con i tacts of theV .relay T.- switch. through the sub- '-f60seribensline'to the aand b leads'A (Figr),

thus energipzing the windings' I andv Il .of relayfA. over thel subscriberss'loop. After con- Y; ftacty'SQaihas been closed, -therelay `V is energized over ziearthycontact 30a, reiay V, bati165 tery, earth. jfivencetherotary magnet Dlof 37e at the end of the impulse train. .'Tl and Pl are energized 1n the `following is err the serv'ce switch DW is energized by impulses due to the self interrupter contact Seidl in the circuit: earth, contacts SM2, S32/U, 33221, Sdl, rotary magnet Dl battery earth; and is thus encrgi Aed until the service s\\'itch 70V over its wiper c2 finds a-potential, whicii was applied to the test lead over-contzwt Gc when relay C was energized. Relay Vl is en Y' gizcd in the following circuit: earth, contact 36a, relayVl, contact 37a, battery, earth. 75 Foi-the moment the relay V2 is still short circuited, buu is energized when the cont: ct 37a operates during the transmission of the impulse train, and remains attracted during the impulse train, so that it does not fall bazcktuntil itis shortcircuitedby Contact Relays circuit: eal h, battery, Contact 4:00, relay T2,

relay "El, wiper c2 of the service switch DV, S5 windings l and Il of relay Pl, resistance VW, earth. `Relay T2 is not operated owing to the hij1 esistance of "W21 The service switch cted when contact 33291 opens the circuit foreenergizing the rotary magnet Dl.;

The operatoris connected up zitter the con- `i'sacts-Bll, Lil'l andetplyfigil.have/been closed. rlhe device for generating oscillations is onlyindicatcd diagrammatically in the figure, it can be` arrangedlikethe device:A RQ in the Fig. 2. As it is connected up over the contacts l2/i2 and 4822, in conjunction with the device Rl atthe subscribers station l) it indicates the subscribei"szstation. When Ithe.operator-short circuits the high ,ohmic 100 resistance RVZ' by pressing the keyTa, relay T2 energized Ain ,the ,previously describe@ test circuit, hence the oscillationgenerator is I`disconnectedE and it does not interfere with the clearness of speech-when.the operator les f speaks to the subscriber.

The `connection,wanted by `thesubscriber .N -is then.' .up vby (the operatorfwith `her number sender or dial. rlhesenderContact 66e energizes the relayf'l over: eartlncon-`- 11o tact. 66.2, wiper @2,-of-theservice switch DWV, relay T3, battery,z ea1th;and :over contact 5.03 the relay Al receives impulses foivposi` tioning the succeeding switch in known manmer. VlAfter impulse .transmissionwthe relay- C falls backowing to ,theopeningof the oillnormal Contact cwhen the switch GW' is scrihers station NF at the end of the conversa- '125 tion, ltheconnection is releasedowingto relay A (Fig) rallingback, whereupon relay Vl also falls back and after it has short `circuited lthewinding Iwof, relay P over. ,the contact 55711, the releasemagnet M'ot the. switch GV: Hf

is energized over: earth, oif normal contact 65k, contacts 64p, (S3/UQ, 61021, magnet M, batk tery, earth. The opening of contact @im also releases the preselector VW.

Fig. l shows an arrangement wherein the devices for generating oscillations provided for thevcalling station are located at the connecting route reached over preselecting devices.

When the subscriber N (Fig. ll) takes down his receiver, the relay R is energized over; earth, battery, resistance Wi', contact 701i,

subscriber N, contact'71t, relay R, earth.

Thereby the call seeker AS1 is started up,

and until it reaches the calling line, its rotary magnet D receives impulses over: earth, contacts 797, 96d, 80p, rotary magnet D, battery, earth, the Contact 96d being a self interrupter. On reaching the calling line, the relays T and P are energized in the circuit: earth, battery,

resistance VVz', contact 7Qr, relay T, wiper c3 of the call seeker AS1, windings I and II ofrelay P, contact 779, earth. By opening the contacts 7025 and 7115 the relay RV is deenergized andthejunctionlineis switchedthrough over thecontacts 74p and 75p. Thereupon the relay A is energized over: earth, battery, relay A, contact 75p, wiper b3 of the call seeker AS1, subscriber N, wiper a3 of the call seeker ASL-contact 7 4p, resistance Wz', earth. Relays T and P are maintained energized in the following circuit: earth, battery, resistance Wi, contact 7 8i, relay T, wiper c3, winding I of relay P, contacts 76p, 78a, earth. At

s the same time as the closing of the contactsl 74p and 75p switches through the junctionk line, the oscillation generator is connected up over the points u and o. This oscillation generator corresponds to the arrangement designated by R1 in the Fig. l.

The energizing circuit of the rotary magnet D is opened at contact 80p. The junction line VL having been taken into use by Vthel sub-` f scriber N, the call seeker ASQ is started up to connect up an idle operator, after the relay R1 was energizedover: earth, resistance Wz', contact 81a, junction line VL, contact 98t1, relay R1, battery, earth. Until the seized junction line has been found, the rotary magnet D1 of the call seeker ASQ is energized over: earth, contacts 94:11, 97d1, 95221, rotary magnet D1, battery, earth. When the junction line VL is found relays T1 and P1 are.

locked in the circuit: earth, battery, resist- .ance We', contact 86t1, relay T1, wiper c4 of the call seeker ASQ, winding'I of relay P1, contacts 91201, 93a1, earth. The energizing circuity of the rotary magnet. D1 is opened at contact 95291. The closing of the contact 87a1 lights the lamp L over: earth,'contacts 87a1,

s 89252., lamp L, battery, earth, thus giving the operator the calling signal.v The head set with the device for generating oscillations shown in Fig. Q is connected to the junction line at the :New follows the usual operation of connecting up the oscillation 'generator for indicati ngthe'calling. subscribers station and the .answering of the call by the operator.` The :latterrthen sets up the desired connectionover the plug and jack, whereupon the relay TQ.

is Venergized over: earth, battery, relay TQ,

plug portion 3, jack bush,earth, while the;

Contact SSQ disconnects the lamp 'After the receiver has been hung up at the subscribers station N, at the end ofthe lconversation, the connection is released owing to the relay A falling back and at Contact 7 8m opening the locking circuit of the relays P and T. Also the lrelay A1 is deenergized by the opening of the contacts 81a and 8211/ Thereby the locking circuit of the relays P1 and .T1 is also opened, so Vthat the junction-31 line becomes free for other calls after the operator receives the clearing lsignal by the v ighting. of the lamp L over :f earth, contacts 88m, QOQ, lamp L, battery, earth; and she has withdrawn the plug.y from the jack.4 `'Thereupon the relay TQ falls back and the lamp is extinguished by the opening ofthe contact 9025Q. The connectionhas now been completely released.`

What is-claimed is:

1. In a telephone system, a calling line, anV

oscillator associated with said line and arrangedto superimpose an alternating current of inaudible frequency thereon, a second'oscillator capable of superimposing an alternate ing current-of a dierent inaudible frequency on said line, and means for connecting said second oscillator to said line to produce an audible beat note indicative of the class of the calling line. j

lator associated with said line for superim posing an alternating current of inaudible frequency thereon, a second oscillator associatedwith said operators position and arranged to transmit an alternating current of a dierent inaudible frequency, and means controlled by the operator for temporarily connecting said second oscillator to said line` to produce an audible beat note indicative of the class of the calling line.

3. In a telephone system, a calling line, means for transmitting an alternating current of inaudible frequency over said line,

Q. In a telephone system, a calling line eX- tending to an operators position, an oscilanoperators position, and meansat said op- 4*erators position tor superimposing analternating current 1 'of dili'erent 'inaudible frequency on'said liiieto cooperate with said irst alteriiating` current iii `producingl an audible `signal to inform the operator of the class of the callingr line.

4. Iii a telephone system, subscribers lines divided into different classes, an operators position, oscillators associated with said lines,

f another oscillator associated With said operators position, means for connecting a calling one of said lines with said position, and means tor 'temporarily interconnecting the oscillator associated With the calling line With said operators oscillator to produce'an audible beatiiote indicative of the class of the calling line.

5.: In a telephone system, subscribers lines divided into different classes, an operators position, oscillators associated With said lines, another oscillator associated with said operators position, means for connecting a calling one of said lines with said position, means rf 25\ orteinporarily interconnecting the oscillator associated with the calling line With said operators-oscillator to produce an audible beat note indicative of the class of the calling line,

and subscriber controlled means for varying the'pitcli of said beat note.

' 6; In combination, a line, means for transe initting a signaling` current of inaudible fre- '-qiieiicy over said line, a source of current at the receiving end of the line'Which is also of f anl inaudible frequency but which differs in frequency from the signaling current being received, means for connecting said source With the line to produce a heterodyiie signal which is audible, and means at the transmitting end of said line for Varying the pitch of V4said signal.

In Witness whereof, I hereunto subscribe my name this 5th day of November, A. D.

" MAXIMILIAN MATHIAS. 

